This invention relates generally to manual multi-speed transmissions of the type used in motor vehicles. More specifically, the present invention is directed to a compact manual transaxle having a locking differential for its reverse gear assembly.
Due to increasing consumer demand for front wheel drive vehicles with more powerful yet fuel-efficient drivetrains, the engine and transaxle must be efficiently packaged to take advantage of all available space within the engine compartment. Concomitantly, most modern transaxles must be capable of providing at least five forward speed ratios. As such, minimizing the overall axial length of the transaxle as well as its shaft center distances is of critical importance to the transmission designer. To meet these requirements, various xe2x80x9cthree-shaftxe2x80x9d type transaxles have been developed that include an input shaft and a pair of output shafts each having an output pinion meshed with a drive gear fixed to the differential. A series of gearsets provided between the input shaft and one or both of the output shafts can be selectively engaged to deliver power from the input shaft to a pair of axle half-shafts secured to the differential. For example, U.S. Pat. Nos. 5,311,789, 5,385,065 and 5,495,775 each disclose this type of transaxle. Additionally, in many manual transmissions, sliding-type gearsets are commonly used for establishing the reverse gear. Alternatively, some manual transmissions are equipped with a synchronized reverse arrangement for preventing the undesirable grinding associated with conventional sliding-type arrangements. Exemplary synchronized reverse gear arrangements are disclosed in U.S. Pat. Nos. 4,558,607, 4,640,141 and 5,385,065. While such arrangements appear to satisfactorily perform their desired function, a need still exists to provide alternatives to conventional reverse gear arrangements.
A problem associated with the above-mentioned transaxle relates to the overall shaft length required. Another problem associated with the above-mentioned transaxle relates to the requirement that both of the output shafts be positioned xe2x80x9cout-of-planexe2x80x9d relative to the plane extending through the input shaft and the differential. In particular, in order to maintain the center distance between the input shaft and the differential required for adequate axle shaft clearances, the transaxle""s input shaft/output shaft center distance and its output shaft/differential center distance must be increased. This results in added geartrain mass and cost while also requiring increased synchronizer capacity.
Accordingly, while such conventional manual transaxle designs attempt to address the packaging requirements mentioned above, a need still exists for development of more compact and robust manual transaxles that can meet the demands of modem front wheel drive vehicular applications.
The primary object of the present invention is to provide a multi-speed manual transaxle that meets the above-noted needs and improves upon conventional designs.
To this end, the present invention is directed to a six-speed manual transaxle comprised of an input shaft having a transfer gear fixed thereto, a reduction shaft having a first reduction gear fixed thereto and meshed with the transfer gear and a second reduction gear rotatably supported thereon, an output shaft having an output gear fixed thereto and a mainshaft having a first input gear fixed thereto, a first speed gear rotatably supported on the output shaft and meshed with the first input gear, a second input gear fixed to the mainshaft and meshed with the second reduction gear, a second speed gear rotatably supported on the output shaft and meshed with the second input gear, a third input gear rotatably supported on the mainshaft, a third speed gear fixed to the output shaft and meshed with the third input gear, a first clutch and a second clutch for selectively coupling the input shaft to the output shaft directly or through a reduction gearset, a third clutch for selectively coupling either of the first and second speed gears to the output shaft, a fourth clutch for selectively coupling the third speed gear to the mainshaft, a locking mechanism operable in a first mode for permitting unrestricted rotation of a carrier assembly and a second mode for inhibiting rotation thereof, the locking mechanism is shifted into its second mode to reverse the direction of rotation of the output relative to the input, thereby establishing the reverse gear, a final drive gear meshed with the output gear, and a differential driven by the final drive gear. Since the mainshaft can be driven either directly or through a reduction gearset, each gear on the mainshaft can result in two different forward speed ratios of the output shaft. Thus, the three gears on the mainshaft produce six forward speed ratios.